Yield:-

Reaction Conditions:

with sodium methylate in tetrahydrofuran;methanol at 0 - 20;

Steps:

Step a

General procedure: To a freshly prepared sodium methylate solution in methanol and THF ethyl trifluoroacetate (1.2 equiv) was added under stirring at 0° followed by addition of ketone 2 (1.0 equiv). The reaction mixture was allowed to stir for additional 3-24 h until the starting materials were consumed, as determined by thin-layer chromatography (TLC). Then the solvent was removed under reduced pressure and the residue was acidified with hydrochloric acid (1 N), followed by extracted with acetic ether. The combined organic layers were dried (MgSO₄), Fitered and the filtrate was concentrated under reduced pressure. The crude product was puried by column chromatography. Yield: 40-90%. For some cases, the crude products can be straight used for step c without the column chromatography procedure.

References:

Wang, Ning-Yu;Zuo, Wei-Qiong;Xu, Ying;Gao, Chao;Zeng, Xiu-Xiu;Zhang, Li-Dan;You, Xin-Yu;Peng, Cui-Ting;Shen, Yang;Yang, Sheng-Yong;Wei, Yu-Quan;Yu, Luo-Ting [Bioorganic and Medicinal Chemistry Letters,2014,vol. 24,# 6,p. 1581 - 1588] Location in patent:supporting information